- Number 430 |
- January 12, 2015
Billions upon billions of neutrinos speed harmlessly through everyone’s body every moment of the day, according to cosmologists. The bulk of these subatomic particles are believed to come straight from the Big Bang, rather than from the sun or other sources. Experimental confirmation of this belief could yield seminal insights into the early universe and the physics of neutrinos. But how do you interrogate something so elusive that it could zip through a barrier of iron a light-year thick as if it were empty space?
At DOE’s Princeton Plasma Physics Laboratory (PPPL), researchers led by Princeton University physicist Chris Tully are set to hunt for these nearly massless Big Bang relics by exploiting a curious fact: Neutrinos can be captured by tritium, a radioactive isotope of hydrogen, and provide a tiny boost of energy to the electrons — or beta particles — that are emitted in tritium decay.
Like snowflakes, nanoparticles come in a wide variety of shapes and sizes. The geometry of a nanoparticle is often as influential as its chemical makeup in determining how it behaves, from its catalytic properties to its potential as a semiconductor component.
Thanks to a new study from Argonne National Laboratory, researchers are closer to understanding the process by which nanoparticles made of more than one material – called heterostructured nanoparticles – form. This process, known as heterogeneous nucleation, is the same mechanism by which beads of condensation form on a windowpane.
Human biology is a massive collection of chemical reactions, from the intricate signaling network that powers our brain activity to the body’s immune response to viruses and the way our eyes adjust to sunlight. All involve proteins, known as the molecules of life; and scientists have been steadily moving toward their ultimate goal of following these life-essential reactions step by step in real time, at the scale of atoms and electrons.
Now, researchers have captured the highest-resolution snapshots ever taken with an X-ray laser that show changes in a protein’s structure over time, revealing how a key protein in a photosynthetic bacterium changes shape when hit by light. They achieved a resolution of 1.6 angstroms, equivalent to the radius of a single tin atom.
Creating extended range electric cars and high-capacity flash memory for portable electronics requires scientists to delve into the behavior of anions, negatively charged molecules, that can store extra electrons needed to get the job done. For the first time, scientists at DOE's Pacific Northwest National Laboratory (PNNL) determined how carefully prepared electron-rich anions interact with three well-known carbon-based surfaces. Unlike positively charged ions, anions retain their charge and fail to transfer electrons to the surface. The Keggin anions refuse to release their electrons to the surface because of the substantial force holding the electrons to the molecule.
"In contrast with positive ions, charge retention by negative ions is less surface dependent," said Dr. Julia Laskin, a PNNL Laboratory Fellow who led the research. "In this case, the properties of the ion determine whether it retains its charge on the surface."